1. Field of the Invention
This invention relates to the field of inflatable mattress devices in general, and, in particular, to inflatable mattresses useful in a health care setting for the prevention and management of skin ulcerations or bedsores.
2. Description of the Prior Art
The usefulness of inflatable mattresses designed to alleviate contact between a long term bedridden patient and the supporting bed surface has long been recognized, and many United States and foreign patents disclose advances and refinements of that technology. Still, shortcoming remain in the prior art devices and particularly in the method of making those devices. Those methods tend to be labor intensive because many separate pieces of sheet material, typically vinyl or urethane sheeting, must be assembled as by radio frequency welding to make the inflatable mattress. Conventional practice has been to weld the pieces individually, a time consuming and therefore costly process. Each precut piece has to be handled manually by a person skilled in radio frequency welding.
The typical mattress configuration involves a base of some kind to which are secured a relatively large number of elongated inflatable chambers or air tubes, each of which spans the full width of the bed. The air tubes are attached to the common base in closely adjacent, mutually parallel relationship to make-up a body support surface.
Various approaches are known for securing the air tubes to a common base, some involving releasable connectors on the bottom of each air tube, others using Velcro type hook-and-loop attachments, for example. Air supply conduits are connected to each air tube for maintaining a desired level of air pressure in each tube. The internal air pressure may be the same in all of the tubes along one bed, or high-low pressure levels may be alternatated in adjacent air tubes in so called alternating air pressure beds, intended to avoid sustained contact against a particular area of the patients body to prevent ulcerations. In all cases, air beds intended for health care use have air chambers which are individually detachable from the base of the bed. While this feature is desirable in that replacement of damaged air tubes is possible without replacement of the entire air bed, it also adds considerably to the cost of manufacture and complicates the set-up and maintenance of the bed.
One piece inflatable mattresses are known, ranging from inexpensive pool floats to better quality heavy duty air mattresses. These, however, are not suitable for use in health care applications because they do not provide individually inflatable air chambers each of which constitutes only a small portion of the patient supporting surface. Furthermore, conventional one piece mattresses are not made by methods which are conducive to making air chambers of arbitrary height, i.e., for making relatively tall air chambers resulting in deep air mattresses, to provide an adequate safety margin against bottoming out of the patient weight onto the base of the air bed under low internal pressure conditions in the air chambers. For this reason, conventional practice requires that each air chamber be formed as a self-contained enclosure, each attached to a common base to make up the air bed. Air distribution is accomplished with small diameter tubing assembled into a complex manifold and individual air connections to each inflatable chamber of the mattress. Manufacture of each such connection entails considerable cost of materials and labor. The result is an air distribution system which constitutes a substantial portion of the total cost of the air mattress.
In U.S. Pat. No. 5,634,225 this applicant has disclosed an air mattress which largely eliminates the need for an external air supply manifold. Instead, air conduits are formed integrally to the common base of the mattress, and each inflatable chamber is detachable connected to the base by means of connectors which also serve as air connectors between the supply conduits and the inflatable chambers. While this approach works well and results in substantial reduction in the cost of the air mattress, there is a continuing need for still lower cost air mattresses suitable for health care applications.